import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        while (scanner.hasNextLine()){
            String str1=scanner.nextLine();
            String str2=scanner.nextLine();
            System.out.println(func(str1,str2));
        }
    }
    public static String func(String str1,String str2){
        StringBuilder stringBuilder=new StringBuilder();

        for (int i = 0; i <str1.length() ; i++) {
            char ch=str1.charAt(i);
            for (int j = 0; j <str2.length() ; j++) {
                if(str1.charAt(i)!=str2.charAt(j)){
                    stringBuilder.append(ch);
                }
            }

        }
        return stringBuilder.toString();
    }
}
